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b=OMJRlayKVif4YbZF9qfw9t+/LZpmyuFR/neasYaN30x+/Uro4/h7gm0L4P9lyLCHp qqxu1PF7g1OZphsraYVBTe2h2BzlfGS9roOjjp0CGJVAz9gaxzXFBSvrI1g6PGu/TA AG53phwplyMHUlFnqmZOzK7SV3q3xudIwDMzm1RJ050OONWzteQf4LsAlt+9Z19pkl KB5knvrBsMnWnHJS7SGYgES1uUDKo/3KrfPU3XKcmPtXVRijp7rwxeJum//6Ef3Mpp xxglyjXdpy51HeLQXm2x28Tt9kDyP5N1YGVcdz03k9pwJEJHXShIqN4J7la3dSu0Jk 4NDIVjwrZmpEA== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , damon@lists.linux.dev, kernel-team@meta.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org Subject: [PATCH 3/6] samples/damon/mtier: support boot time enable setup Date: Sun, 6 Jul 2025 12:32:04 -0700 Message-Id: <20250706193207.39810-4-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250706193207.39810-1-sj@kernel.org> References: <20250706193207.39810-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 628BAC0008 X-Stat-Signature: z7ygauado5wipkybzjkjxbo8s3edapes X-HE-Tag: 1751830335-903229 X-HE-Meta: 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 o/VrYdeo xUH/wmT5PljXiDJ5Ayv9oT+oJBRhVzojconj41mtL6S5lbL0BhetRglCVLA+cpyyc/k5OaaLsraQt/XhGkptniX+Rg8FQ6+5ZBPJxv0QoShDTjagTPI7gPkVfhSSq0/7YNbPe+cZ1kGoRvZ3Ci3fKDI0FVWCqn8jtAjNeHLSJbRcrOC6QLyyy6M64fXvq6cdgexpqX0jSvM9SNXovCl584ehHFof5+idAf/nF8SveU1ozaNs= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: If 'enable' parameter of the 'mtier' DAMON sample module is set at boot time via the kernel command line, memory allocation is tried before the slab is initialized. As a result kernel NULL pointer dereference BUG can happen. Fix it by checking the initialization status. Fixes: 82a08bde3cf7 ("samples/damon: implement a DAMON module for memory tiering") Cc: stable@vger.kernel.org Signed-off-by: SeongJae Park --- samples/damon/mtier.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/samples/damon/mtier.c b/samples/damon/mtier.c index 97892ade7f31..20c3102242ec 100644 --- a/samples/damon/mtier.c +++ b/samples/damon/mtier.c @@ -157,6 +157,8 @@ static void damon_sample_mtier_stop(void) damon_destroy_ctx(ctxs[1]); } +static bool init_called; + static int damon_sample_mtier_enable_store( const char *val, const struct kernel_param *kp) { @@ -170,6 +172,9 @@ static int damon_sample_mtier_enable_store( if (enable == enabled) return 0; + if (!init_called) + return 0; + if (enable) { err = damon_sample_mtier_start(); if (err) @@ -182,6 +187,14 @@ static int damon_sample_mtier_enable_store( static int __init damon_sample_mtier_init(void) { + int err = 0; + + init_called = true; + if (enable) { + err = damon_sample_mtier_start(); + if (err) + enable = false; + } return 0; } -- 2.39.5